Not Applicable
Not Applicable
1. Field of the Invention
The invention relates to an apparatus for displaying a stereoscopic image for use in computer graphics, television, virtual reality, and the like.
2. Description of Related Art
Stereoscopic viewing is a process that tricks the brain into thinking that it is seeing a three-dimensional image. This is accomplished by a viewer having one eye see a slightly different perspective than the other eye. Stereoscopic devices, such as the old Stereoscopes, or the more modern VIEW MASTER((trademark)) utilized this concept. They consisted of two separate photographsxe2x80x94one representing the right eye""s viewpoint, and the other the left eye""s viewpoint, with the stereoscopic device separating the two. The viewer looks into the device and the right eye sees the right eye viewpoint and the left eye sees the left eye viewpoint, and the brain is tricked into thinking that it is was seeing one three-dimensional image. Although they achieved three-dimensional viewing, these devices suffer from the fact that they can only display still images.
Various methods for displaying moving stereoscopic images have been proposed. One attempt was the ANAGLYPHIC system. Since the brain needs two different viewpoints to achieve a three-dimensional effect, this system blends the two viewpoints into one picture, highlighting one of the viewpoints in blue, and the other viewpoint in red. The viewers of this system are required to wear special glasses. One lens of the glasses is tinted red while the other lens is tinted blue. The theory being that the red lens filters out the red highlighted image allowing the eye to see only the blue image, while the blue lens filters out the blue image allowing only the red image to be seen. This use of chromatic distinctions through color filters eliminates the possibility of displaying a full-spectrum stereoscopic image.
Another attempt to achieve stereoscopic displays was the use of lenticular screens. In this method, two viewpoints (one right-eye and one left-eye) are interlaced by narrow vertical strips from each viewpoint into one image. A lenticular screen is positioned in front of the image with the lenticules having the property of separating the right-eye viewpoint from the left-eye viewpoint and presenting each viewpoint to each appropriate eye, creating a somewhat low quality stereoscopic display.
U.S. Pat. No. 2,209,747 (Eisler) discloses a similar system, but instead of a lenticular screen a screen made of a plurality of very narrow vertical slits is placed in front of an image that has been interlaced similar to that of a lenticular method. When a viewer, the slits, and the image are properly positioned, a stereoscopic display is achieved, because the slits allow the viewer""s right-eye to view only the right-eye viewpoint and the left-eye to view only the left-eye viewpoint. This method is known as the HESS system of displaying a stereoscopic image. Since the slits have to be very narrow, and since each eye is really only being presented with half of a picture (every other adjacent vertical strip of the entire picture), such a system suffers from a loss of resolution.
Another attempt to create stereoscopic three-dimensional viewing uses polarized glasses. One eye of the viewer""s glasses is given polarized characteristics 180 degrees out of phase with the other eye. One field or frame of the display is shown with one eye""s polarized characteristics, preventing the other eye from viewing the image. The succeeding field or frame reverses the polarized characteristics allowing the second eye only to view its viewpoint. Early systems used a regular television set with a special screen. The top half of the screen is polarized 180 degrees out of phase with the bottom half. One of the necessary two viewpoints for three-dimensional viewing is displayed on the top half of the screen, while the second viewpoint is simultaneously broadcast on the bottom half. When the viewer put on the special polarized glasses, one eye saw only the top half, while the other eye saw only the bottom half. Several variations of this method have been demonstrated. The polarized characteristics of the image screen can be switched (passive system) or the lenses of the glasses themselves can do the polarization switching (active system). Systems with an effective frame rate of 15 frames per second have been developed by HONEYWELL, PANASONIC (MATSUSHITA), and MEGATEK. Although polarized optics have lead to several elegant methods for displaying stereoscopic images, they still require the use of individual selection devices (glasses).
Virtual Reality (VR) is an application ripe for stereoscopic display systems, and several of the previously mentioned prior arts have been employed. Headsets featuring glasses with two tiny LCD screens viewed through magnifying lenses have been developed (such as those developed by DISPLAYTECH) to create stereoscopic displays in a method very similar to the old Stereoscopes or VIEW MASTER((trademark)). Each eye is optically prevented from seeing the other eye""s screen, thus producing a stereoscopic display. These systems can suffer anything from low-quality, to tiny viewing screens, to sheer bulk for all the components necessary to the system.
It is the object of the present invention to provide an improved apparatus for displaying full spectrum, full-motion, stereoscopic images.
It is a further object of the present invention to provide an apparatus for displaying stereoscopic images without the requirement of using special polarized glasses.
Other objects of the present invention will be apparent from the following description of the invention.
My invention is a stereoscopic display unit that uses a flat surface display screen having individual picture elements (pixels) arranged in a grid pattern across its surface. This display screen can display full spectrum images at a sufficient frame rate to prevent undesirable flicker. The display screen also can display an image composed of a plurality of stereopairs: two viewpoints (one right-eye and one left-eye) interlaced by vertical rows of pixels. By displaying said interlaced image, only one half (every-other vertical line) of each right-eye and one half of each left-eye viewpoint is displayed during each frame. The display screen can display the image during one frame. During the succeeding frame, it displays the complimentary image (the undisplayed vertical rows of pixels from each of the right-eye and left-eye viewpoints). For example, if the first vertical row of pixels (far left row) of the first frame is from the right-eye viewpoint, then the first vertical row of the succeeding complimentary frame is from the left-eye viewpoint. A masking screen comprised of a plurality of regularly spaced, vertical apertures is positioned in front of, parallel to, and in a geometric relation with said display screen. This screen lies between the viewer and the display screen. These apertures (or shutters) are made so that only the even numbered shutters are open during one frame, and only the odd numbered shutters are open during the succeeding frame.
When a viewer is positioned so that the open shutter permits the right eye to see only the vertical row of pixels of the interlaced image displaying the right eye viewpoint, while allowing the left eye to see only the left eye viewpoint row, a stereoscopic image of low (one-half) resolution is displayed. During each succeeding frame, the open shutters close, the closed shutters open, and the complementary interlaced image is likewise displayed. When this process is repeated, two high resolution, full spectrum viewpoint images are presented, one to each of the appropriate eyes of the viewer, thus creating a full motion, high resolution, full spectrum stereoscopic display. The masking screen can adjust the parallel distance between the display surface and the masking screen to accommodate the necessary geometric relationship between the display surface, the masking screen, and the viewer(s). Finally, the shutters are constructed such that all shutters can be switched to the open state if the stereoscopic effect is not desired.